Triportheus orinocensis, Malabarba, 2004

Malabarba, Maria Claudia S. L., 2004, Revision of the Neotropical genus Triportheus Cope, 1872 (Characiformes: Characidae), Neotropical Ichthyology 2 (4), pp. 167-204 : 198-200

Triportheus orinocensis , new species

Fig. 25

Holotype. MZUSP 85804 , 85.49 mm SL. Venezuela, Guarico, caño to West of road from Calabozo to San Fernando , about 35 km south to Fundo Masaguaral , caño Falcon , R. Vari et al., 20 Jan 1983 (8º14’N, 67º35’W).

Paratypes. Venezuela: Guarico: MZUSP 27968 (7,62.5- 79.2 mm SL), same data as holotype . USNM 258037 (7, 65.8-124.8 mm SL), ponds to W of caño Falcon, R. P. Vari et al., 20 Jan 1983 (8º14’N, 67º35’W) ; USNM 260134 (7, 87.3-93.7 mm SL), río Caracol where crossed by bridge on ranch, Fundo Masaguaral, R. P.Vari et al., 20 Jan 1983 (08°34’N, 67°30’W) ; INHS 98930 (2, 76.6-85.4), UNELLEZ51999 (3,76.6-82.1mmSL) , ANSP180379 (1, 85.8 mmSL), MBUCV-V-32265(3,74.1-85.9) , MCP 35825 (1, 102.6 mm SL), 74.1-76.6 mm SL, río Apurito, at mouth of río Guariquito , J. W.Armbruster & P. Ceas, 14 Jan 1995 (07°48’N, 66°31’W) ; INHS 35870 (2, 81- 112.9 mm SL), río Cajauito SE of “El Carote” near mouth, D. C. Taphorn et al., 12 Jan 1995 (07°41’N, 66°21’W) ; INHS 69510 (1, 134.5 mm SL), río Los Aceites , 15 km SSE of Palenque, D. C. Taphorn, L. M. Page, K. S. Cummings & D.A. Carney, 21 Jan 1986 (08°52’N, 66°54’W). Portuguesa: INHS 35635 (1, 104.7 mm SL), caño Maraca on road from Guanare to Guanarito at 60 km marker, P.A. Ceas, J. W.Armbruster et al., 1 Jan 1995 (8°49’N, 69°20’W) ; INHS 98929 (5, 73.8-144.3 mm SL), Puerto Papelon, caño Igues, D. Rodriguez & P. Pacheco, 17 Dec 1992 (8°34’N, 68°5’W) ; USNM 348707 (5, 58.3-68.3 mm SL), río Portuguesa, caño Maraca, J. W. Armbruster et al., 24 Dec 1998 (8º49’N, 69º20’W). Cojedes: INHS 32014 (1, 68.6 mm SL), río San Carlos , caño Hondo, 5 km S of Las Vegas (9°34’N, 68°5’W). Apure: USNM 257992 (2, 71.5- 74.6 mm SL), side channel of río Apure 5k W of San Fernando de Apure, technicians at Apure fisheries, 21 Jan 1983 (07°53’N, 67°29’W); USNM 258120 (4, 57.5-67.5 mm SL), río El Canito where crossed by road from San Fernando to Cunaviche, 22 Jan 1983 (07°28’N, 67°39’W). Bolivar: USNM 233640 (12, 66.2- 85.3 mm SL), Los Castillos, isolated lagoon on isla Tapatapa , Marsh et al., 10 Nov 1979 (08°31’N, 62°26’W); USNM 233225 (1, 101.9 mm SL), caño Araguaito, 129 km from sea buoy, J. Baskin & D. Stewart, 13 Nov 1979 (08°40’N, 62°51’W).

Diagnosis. A deep-bodied Triportheus species reaching 144.3 mm of SL (depth at dorsal-fin origin, 28.7-37.1, mean = 33.4% SL, n = 58; depth at pectoral-fin insertion, 32.2-39.3, mean = 35.6% SL, n = 58). This species is readily distinguished from its congeners by the extensive scaling over the caudal and anal fins. The presence of 2 longitudinal scale rows between the pectoral-fin insertion and the ventral keel distinguishes this species from elongate-bodied Triportheus species that have 1 longitudinal scale row between the pectoral-fin insertion and the ventral keel. Triportheus orinocensis further differs from deep-bodied congeners, by the combination of the number of gill rakers on the lower limb of the first gill arch (24-28, mean = 25.8, n = 37); the number of branched anal-fin rays (28-32, mean = 29.9, PROOFS n = 35); and the number of lateral-line scales (34-39, mean = 37.2, n = 31).

Description. Morphometric data for Triportheus orinocensis presented in Table 17. Body deep and laterally compressed. Greatest body depth located slightly posterior to vertical through pectoral-fin insertion. Dorsal profile of head straight from margin of upper lip to rear of head. Dorsal profile of body gently curved from rear of head to dorsal-fin origin; posteroventrally slanted from dorsal-fin origin to caudal peduncle; straight along caudal peduncle. Laterodorsal portion of body slightly keeled.

Ventral profile of head straight from margin of lower lip to anteroventral margin of dentary. Ventral profile of body arched from base of dentary to pelvic-fin insertion; nearly straight from that point to anal-fin origin; gently curved along analfin base; straight along caudal peduncle. Prepelvic region distinctly expanded ventrally and laterally flattened, with well-developed keel.

Head blunt in profile; posterior margin of opercle falling short of pectoral-fin insertion. Snout vertically straight. Mouth terminal; lower jaw as longer as upper jaw. Nostrils of each side close together; anterior opening circular; posterior elongate.

Gill rakers thick and separated, length equivalent to one-half length of branchial filament; gill rakers on lower limb of first arch 24-28 [25] (mean = 25.8, n = 37).

Teeth on premaxilla in 3 rows; with teeth of inner row largest. Four to 5 tricuspidate teeth on outer row; outer row teeth arranged along external margin of mouth and visible externally in closed mouth. Medial tooth row with 3 tricuspidate teeth. Seven multicuspidate teeth on inner row of premaxilla. Maxilla with 2-3 tricuspidate teeth smaller than those of premaxilla. Teeth on lower jaw in 2 rows, outer row with 5 larger tricuspidate to pentacuspidate teeth, followed by 3-4 much smaller, tricuspidate teeth.

Scales cycloid, thin, and large. Lateral line distinctly decurved ventrally, completely pored from supracleithrum to base of caudal-fin rays. Thirty-four to 39 [39] (mean = 37.2, n = 31) scales in lateral line; seven scale series between lateral line and dorsal-fin origin; 2 scale rows from lateral line to pelvic-fin insertion. Two scale rows between pectoral-fin insertion and midventral keel; 5 scale series on caudal peduncle. Scales along mid-dorsal line very irregular, with 6-13 [9] (mean = 8.4, n = 17) scales from tip of supraoccipital spine to dorsal-fin origin.

Dorsal-fin rays ii,9; anal-fin rays iii,28-32 [29] (mean = 29.9, n = 35); pectoral-fin rays i,10-13 [11] (mean = 11.6, n = 36); pelvic-fin rays i,6. Dorsal-fin margin straight, situated on posterior one-half of body; base of last dorsal-fin ray situated approximately along vertical through base of seventh anal-fin ray; second unbranched and first branched dorsal-fin ray slightly longer than following rays. Pectoral fin pointed, tip extending posteriorly to vertical through middle of pelvic fin. Anal fin margin slightly curved, first branched anal-fin ray longest, and following rays gradually decreasing in length. Four or five series of scales overlying basal portions of anal-fin rays, and covering one-half of length of rays. Margin of caudal fin truncate to slightly rounded. Scales covering nearly entire fin.

Total vertebrae 37-38 [37].

Coloration in alcohol. Overall ground color yellowish brown. Snout and dorsal portion of head dark. Some scattered dark chromatophores present on opercle. Body with dark midlateral stripe extending from supracleithrum posteriorly to caudal peduncle; stripe expanding vertically posteriorly and broadened into wider diffuse dark spot on lateral surface of caudal peduncle. Body darker dorsal to stripe. Dorsal-fin rays lightly outlined by dark chromatophores. Scattered chromatophores distributed all over pectoral fin; with more intense pigmentation on first unbranched ray and along fin margin. Caudal-fin border dark.

Distribution. Río Orinoco basin ( Fig. 23 ).

Etymology. Species name, orinocensis , from the Río Orinoco, where the new species occurs. The name is treated as a name in apposition.

Figures

Fig. 25. Triportheus orinocensis, holotype, MZUSP 85804, 85.49 mm SL, Venezuela, Guarico, caño Falcon.

Fig. 23. Map of central and northern South America showing geographic distribution of Triportheus magdalenae (circles; asterisk = type locality), T. pantanensis (black squares; white square = type locality) and T. orinocensis n. sp. (triangles; white diamond = type locality) (some symbols represent more than one locality or lot of specimens).